Grease composition



United States Patent 3,269,949 GREASE COMPOSITiON Arthur C. Borg,Chicago, 111., assignor to Standard Oil Company, Chicago, 111., acorporation of Indiana No Drawing. Filed Aug. 30, 1963, Ser. No. 305,8325 Claims. (Cl. 25242.1)

This invention relates to improved lubricating metal soap greases andparticularly to lithium soap greases.

It has been discovered that the use of about 0.25- Weight percent,preferably about l-6 weight percent, of methyl hydrogen silicone fluidin conventional lubricating metal soap greases improves the lubricityand functional properties of such greases. In addition to suchimprovements, it was unexpectedly found that use of methyl hydrogensilicone fluid improves the grease yield and its high temperaturestability. While the prior art suggests that methyl hydrogen siliconefluid can be used as a lubricant or as a vehicle for grease undernon-oxidizing conditions, the discovery that such fluids in thelubricating oil viscosity range, when used in small amounts, in metalsoap greases under oxidizing service conditions would act as a lubricityimprover was quite surprising and unexpected and in no way predictable.

Lubricating metal soap greases are well known in the art. Such greasesare formed by thickening lubricating oil vehicles with metal soaps asthe thickening agents. Such metal soaps are the alkali metal and thealkaline earth soaps or unsaturated, partially unsaturated, or saturatedfats or fatty acids or hydroxy fatty acids derived from animal,vegetable or marine sources. A fatty acid constituent of such soaps hasat least 12 carbon atoms, and preferably from about 12 to 22 carbonatoms. Exemplary of the fatty acids used in preparing metal soapthickening agents are the lauric, myristic, palmitic, stearic, behenic,oleic, hydroxy-stearic, acids, as well as the hydrogenated fish oilfatty acids, hydrogenated castor oil, and mixtures thereof. Exemplarymet-a1 soaps are lithium stearate, lithium lZ-hydroxy stearate, sodiumstearate, barium stearate, strontium soap of hydrogenation fish oilfatty acids, barium-12-hydroxy stearates, calcium soap of hydrogenatedcastor oil, potassium stearate, etc. Mixtures of such soaps can also beused.

Lubricating oil vehicles that are used in preparing met-a1 soap greasescan be petroleum oils in the lubricating oil viscosity range, i.e., fromabout 25 SSU at 100 F. to about 300 SSU at 310 F. or synthetichydrocarbon oils such as are obtained by the polymerization ofunsaturated hydrocarbons. Other oleaginous materials within thelubricating oil range can be used, such as, for example high molecularweight polyoxyalkylene compounds such as polyalkylene glycol and estersthereof; aliphatic diesters of dicarboxylic acids such as the butyl,hexyl, ethyl hexyl, decyl, lauryl, etc. esters of sebacic acid, adipicacid, azealic acid, etc.; polyfluoro derivatives of organic compounds,particularly hydrocarbons, such as trifluorovinyl chloride polymer,trifluorochloroethylene polymer, etc.

The term methyl hydrogen silicone fluid as used herein and in the claimsrefers to the liquid methyl hydrogen siloxane polymers in thelubricating oil viscosity range. Such polymers are represented by theformula wherein n represents an integer that is suflicient for suchpolymers to have a viscosity in the lubricating oil viscosity range,namely, of about 25-3500 SSU at 100 F., preferably of about 100-1250SSU. Such polymers and their preparation are fully described in US.2,491,843.

Illustrative of the improved soap greases of the present invention aremulti-purpose lithium soap greases. Such greases are prepared byconventional procedures by the use of from about 5-25 weight percent ofa lithium soap, as a thickening agent, in a lubricating oil. Forexample, a solvent-extracted SAE 40 grade petroleum oil was thickened togrease consistency with 8 weight percent lithium soap obtained from theneutralization of a mixture of hydrogenated castor oil and hydrogenatedfish oi-l fatty acids with lithium hydroxide. This grease had a Timkenvalue of 15 pounds and an ASTM penetration of 304. To a portion of thisgrease was added 1 weight percent of methyl hydrogen silicone fluid (GE398-72-857 having a viscosity of about SSU at F., a viscosity index ofabout 200, a pour point of less than -80 F., and a specific gravity of1.0050 at 25 C.). After milling, the finished grease containing themethyl hydrogen silicone fluid had a Timken value of 25 pounds, an ASTMpenetration of 294 and improved thermal stability at 200 F. Theimprovement in the Timken value and the reduction in the ASTMpenetration value of the lithium soap grease obtained by the addition ofthe methyl hydrogen silicone fluid illustrates the substantialimprovement obtainable by the use of methyl hydrogen silicone fluid. Theincrease in the Timken value shows that the load beaning property ofsuch greases is substantially improved. The reduced ASTM penetrationvalue shows that the inclusion of methyl hydrogen silicone fluid in asoap grease produces a harder grease. Consequently, it is possible toobtain a greater yield per pound of thickener.

It will be apparent to one skilled in the art that methyl hydrogensilicone fluid is a very effective lubricity improver and yield improveradditive for conventional lubricating metal so-ap greases.

It is to be understood that the greases of the present invention cancontain added constituents such as antioxidants, oiliness agents,extreme pressure additives, antifoam agents, etc., without in any Waydeparting from the scope of the invention.

I claim:

1. The lubricating grease composition consisting essentially of (A) ahydrocarbon lubricating oil; (B) about 525 weight percent of a fattyacid metal soap thickening agent; and (C) about 0.25-10 weight percentof a methyl hydrogen silicone fluid in the lubricating oil viscosityrange.

2. The grease composition of claim 1 wherein said lubricating oil ispetroleum lubricating oil.

3. The grease composition of claim 2 wherein said metal soap is alithium soap.

4. The grease composition of claim 3 wherein said lithium soap isderived from a mixture of hydrogenated castor oil fatty acids andhydrogenated fish oil fatty acids.

5. The grease composition of claim 4 wherein the amount of said siloconefluid is about 1-6 percent.

References Cited by the Examiner UNITED STATES PATENTS 2,491,843 12/1949Wilcock 252-49.6 3,145,175 8/1964 Wright 252-42.1

FOREIGN PATENTS 926,700 5/1963 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

I. VAUGHN, Assistant Examiner.

1. THE LUBRICATING GREASE COMPOSITION CONSISTING ESSENTIALLY OF (A) AHYDROCARBON LUBRICATING OIL; (B) ABOUT 5-25 WEIGHT PERCENT OF A FATTYACID METAL SOAP THICKENING AGENT; AND (C) ABOUT 0.25-10 WEIGHT PERCENTOF A METHYL HYDROGEN SILICONE FLUID IN THE LUBRICATING OIL VISCOSITYRANGE.
 2. THE GREASE COMPOSITION OF CLAIM 1 WHEREIN SAID LUBRICATING OILIS PETROLEUM LUBRICATING OIL.
 3. THE GREASE COMPOSITION OF CLAIM 2WHEREIN SAID METAL SOAP IS A LITHIUM SOAP.